Artificial leather fabrication



v of artificial leather,

Patented Feb. 2, 1932 same srA WALLACE B. van ARSDEL, or BERLIN, nnw rrnmrsnmnnssrenoa 'ro Brown comrm, or BERLIN, mw'nnmrsmn, A conronn'rron or MAINE ARTIFICIAL ZEATHER, FABRICATION No Drawing.

This invention relates to thefabricatioii more particularly of the type comprising a foundation of mterfelted cellulose fibers impregnated throughout with rubber. Such "a product is useful in making various articles, suchas shoes, upholstered furniture, automobile tops,,travel1ng bags,

' and the like. It has been found that a powhen it is desired that the resu rous web of interfelted cellulose fiber made on machinery of the .papermaking'type serves well as the foundation material particularly lting product have characteristics closely simulating. thoseof natural leather. When a web.of the char acter described isimpregnated with a rubbercarrying vehicle such as the so-called rubber solutions in organic solvents, or aqueous dis- 'persions of rubber, and the liquid vehicle ,then removed, the resulting product has-high flexibility, tensile strength, and tear'resistance, and is resilient and of sufficient porosity to be 'used in the manufacture of innersoles which permit I breathing of the foot and which absorb perspiration therefrom. In some methods of shoemaking, it is desired to dispense with a so-called sock lining on the "innersole, but where this is done, the inner surface of the innersole should be finished tov provide good appearance and suitable feel to the foot. When artificial leather-such as de scribed is finished and embossed to produce the desired appearance and feel, under theheavy pressure employed, in embossing it becomes so compacted and loses so much resiliency and porosity as to be unacceptable for the purpose desired. I y

In accordance with thepresent invention, I produce an artificial leather from a plurality of rubber-impregnated plies of inter- I felted cellulose fiber, a-surface ply being suitably finished and embossed before being bonded with the other ply or plies. vBy finishing and embossing only a surface ply which maybe a comparatively thin sheet, it is possible to produce a product having not only the desired appearance and feel but also having the resiliency and porosity desired in such articles as inners'oles. I

In producing the artificial leather of the presentinvention, I prefer to use a highly Application filed September 30,1929. Serial No. 396,412.

porous web of loosely felted cellulose fiber as the foundation material, for, when such a web is impregnated with a suitable rubbercarrying liquid vehicle, upon the removal of theliquid vehicle, the rubber serves to bind together strongly the fibers of the foundation, and at the same time sufiicient porosity is restored thereto so that it is resilient andcapable of readil absorbing moisture. Preferably, the rub er-impregnated web to serve as the surface ply of the finished'prodnot is of lower rubber content than the other ply or plies, so that after this ply is finished with suitable materials such as lacquers, and' then embossed, it will have greater porosity than were a ply of higher rubber content em-' ployed. In making an artificial leather for use in the manufacture of innersoles, the:

surface ply may have a rubber ficontent of, say, about to 90%, based on her, whereas the other ply or plies may have a rubber content of, say, about 100% to 200%, also based on fiber. The use of plies of difierent rubber content in the production of an artificial leather to be used in the manufacture of innersoles is not, however, my sole invention, this feature being disclosed and claimed in application Serial No. 395,744, filed'September 27, 192?, by George A. Richter and 5 myself.

A procedure which may be followed in producing the product of th present invention, may be substantially as follows. A fluffy web composed of looselyiinterfelted cellulose fibers and possessing high porosity is preferably used as the foundation material for all the plies. A web of unusually high porosity may be 'producedby using a substantially unbeaten wood fiber of high alpha cellulose content, say, 94% or 'greater,'as a raw mapapermaking machine designed tb efl'ect dewatering and drying of the web without the application of' the heavy pressures used in ordinary papermaki'ng practice. ,While other fibers in substantially unbeaten condi-v tion, such as sulphite, kra ft, or" soda pulp,

wood fiber of high alpha cellulose content is terial, and forming such fiber into a web on a may be employed, a substantially unbeaten 1 preferred, because it is more highly absorp a bath of as described in application Serial No. 37 3,055

tive than the usual unbeaten commercialpersion,

wood fibers, and hence enhances the absorptivity or porosity resulting from theloosely felted, uncompacted condition of the fibers. The dry, porous web may be passed through rubber-carrying vehicle such as an ammonia-preserved latex of a solids content of, say, about 16%, at which content immersion for about five to thirty seconds effects a thorough impregnation of the web. If to be used as the surface ply of the sole, the impregnated web may be squeezed until its rubber solids content is about 70% to 90%, based on the weight of dry fiber, and if to be used as the other plies, until its rubber 5 solids content is about 100% to 120%. In

order to prevent migration of the rubber globules to the surface of the web during drying, the ammonia-preserved latex may be treated with the oxide of an amphoteric metal, preferably zinc oxide, as described in application Serial No. 369,267, filed June 7, 1929, by Roger B. Hill, or with alkaline earth metal hydroxides, preferably slaked lime,

filed June 22, 1929,]oy Roger B. Hill. When slaked-lime is the compound added to the latex to overcome migration tendencies during drying, protective colloids such as soluble soaps" or caseinates which are capable of be ing precipitated by lime as insoluble calcium soaps or caseinates, are preferably added to the latex prior to the addition of the slaked lime, in order to overcome coagulating tendencies. Such treatment of the latex prior 'to its use for the impregnation of the Web makes possible the production of a dried,

rubber-impregnated web of uniformity in re spect of rubber distribution therethrough, as troublesome non-rubber constituents of the latex, namely, the proteins and the resins, are converted to an insoluble, inert condition. Apparently, setting or coagulation of the rubber by drying is so retarded by the proteins and resins which exist respectively in an ammonia-preserved latex as Water-soluble proteinates and alkali resinates, that there is a tendency for rubber particles to migrate to the surface of the impregnated product,

Where evaporationof water is taking place.

(1 The tendency for migration of rubber particles is especially pronounced in the case of highly porous webs of cellulose fiber ofthe type described, evidently because of the high capillarly action takingplace during drying to cause such migration.

If desired, a vulcanized latex may be used, so that when the latex-impregnated web is subsequently dried, the rubber will be coco agulated in the Web in vulcanized condition.

Or artificial aqueous dispersions may be used in lieu of natural latex.' Suitable rubbercompounding materials, Vulcanizing agents, and accelerators of vulcanization may be as added to the artificial or natural rubber disso that the dried rubber-impregnated web may be vulcanized under the action of heat, if desired;

The web used as a foundation material for all the plies is preferably comparatively thin. In actual practice, a web of about 100 pounds basis weight (i. e., the weight of 2880 sq. ft. of web) may be employed to good advantage. The impregnated web is of insufficient thickness for the manufacture of products such as innersoles, so that it is necessary to bondtogether two or more webs. In accordance with the present invention, the impregnated web to be used as the surface ply is suitably finished and embossed into a finished product of the desired thickness. To this end, a single web impregnated to a rubber content of preferably about 70% to may be finished according to the colqr, gloss, grain, and Wearing qualities desired. The most durable of the finishes with which I am familiar are thenitroecellulose lacquers, as they impart gloss and smoothness to the sole and are permanent against the action of perspiration. The lacquer maybe applied to the surface of the web as by spray ing, whereupon the coated product may be dried. The lacquered surface may then be embossed under heavy pressures, to produce grain effects simulating those of natural leather, the finished and embossed ply being of much greater compactness than the original rubber-impregnated web. The finishing and embossing treatment may include additional steps to ensure a finish of sufficient thickness and covering power. For instance, an initial 'or base coat of clear nitrocellulose lacquer may be applied to the surface of the sheet, whereupon one or more coats of nitiocellulose lacquer containing suitable pigments or fillers may be applied. The base coat prevents sinking of the pigments or fillers into the rubber-impregnated V cellulose lacquer coatings, are of greater porosity. The finished sheet may then be embossed, as previously described.

The finished embossed sheet may then be bonded with one or more other sheets having a rubber content of about 100% to 120%, a rubber adhesive such as latex preferably being used as the bonding material. It has been found advantageous to moisten the wet surfaces of the dried, rubber-impregnated sheets, and then to apply comparatively thick, concentrated latex as the bonding material, whereupon the sheets may be superposed, united under comparatively slight pressure, and dried. A parently the initial moistefling or setting the plies promotes penetration of the thick latex into the surface portion of the plies, and results in a v better interlocking or bonding together 0t the latex is face-to-face relationship after dried. The resulting product may be cut into innersoles or other shoe parts, or be used for any other articles-where characteristics such as possessed thereby are desired.

I claim:

1. An artificial leather product compristhe plies in ing a plurality of rubber-impregnated plies I of celulose fibers, the surface ply only being finished and embossed and'having greater compactness than the rest of the product.

2. A method which comprises finishing and embossing a porous, rubber-impregnated web of interfelted cellulose fibers, bonding it as a surface ply with one or more other porous, rubber-impregnated webs of interfelted cellulose fibers, and cutting into innersoles.

3. An artificial leather product comprising a plurality of rubber-impregnated plies of cellulose fibers, includin a relatively thin surface ply, said surface p y only being fin- I ished and embossed and having greater compactness than the restof the product.

In testimony whereof I have afixed my signature. 

